In my case, I drive a 2002 E53 3.0d. I replaced the rear driver side air bag. after 2 months the other side leaked. I suggest to all owners with rear self levelling suspension to replace both air bags same time to avoid the inconvenience of going back to the shop again...:D

Just want to thank everyone here. Like X5Tanya, I have the 01 4.4 with only the rear air springs. Reading all this helped me diagnose that they were leaking. Found them on eBay for $199 for the pair, lifetime warranty. Replaced them myself in about 2 hours. Easier than changing brake pads. Just need to be sure to jack up both rear wheels at once so that suspension drops enough to have room to get them out. Work only under a vehicle that is safely supported! (Or pay a shop to do it.)

Can you share the links on Ebay where you found the bags? I need to do the front ones on my 2006 4.8is ! it's leaking badly now and I don't want to burn the compressor by overusing it. Thanks

The eBay item number is 220800059946, listed as NEW REAR AIR RIDE SUSPENSION SPRINGS BAGS BMW X5 E53. You should be able to search eBay Motors for it. Seller is listed as arnott_air_suspension from Cape Canaveral, FL. You could also probably contact them at Arnott, Inc., 1-800-251-8993, or on web at arnottairsuspension.com. My guess is that the price will be different for your model and due to them being the front air springs, etc. Still maybe a bargain!

Have to agree and I just finished the front set in about 1:30 this morning! Really not a big deal!